Electric actuator

ABSTRACT

An electric actuator attached to a vehicle is provided and includes: a motor unit, a speed reducer, a circuit board, an output section, and a housing that accommodates the motor unit, the speed reducer, the circuit board and the output section. The housing has a motor case that opens at one side in an axial direction, and a circuit board case attached to one side of the motor case in the axial direction to close an opening of the motor case and accommodates the circuit board. The motor case has a motor case main body that accommodates the motor unit, and multiple attaching leg sections protruding from the motor case main body and fixed to the vehicle. The attaching leg sections protrude outward from the circuit board case when seen in the axial direction.

CROSS REFERENCE TO RELATED APPLICATIONS

The application claims priority under 35 U.S.C. § 119 to Japanese PatentApplication No. 2017-253677 filed on Dec. 28, 2017, and the entirecontent of which is incorporated herein by reference and made a part ofthis specification.

BACKGROUND Technical Field

The disclosure relates to an electric actuator.

Description of Related Art

An electric actuator including a motor unit, a speed reducer connectedto the motor unit, and an output section to which rotation of the motorunit is transmitted via the speed reducer is known, and mounted on anautomatic transmission configured to change a speed of an engine outputfor travel of a vehicle.

The above-mentioned electric actuator is attached to a vehicle using,for example, a dedicated bracket. However, in this case, the number ofparts increases to an extent of the bracket, and labor for attaching theelectric actuator to the vehicle increases.

In consideration of the above-mentioned circumstances, the disclosureprovides an electric actuator capable of reducing labor for attachmentto a vehicle.

SUMMARY

An aspect of an electric actuator of the disclosure is an electricactuator attached to a vehicle, and the electric actuator includes: amotor unit, having a motor shaft extending in an axial direction; aspeed reducer, connected to one side of the motor shaft in the axialdirection; a circuit board disposed at one side of the speed reducer inthe axial direction and electrically connected to the motor unit; anoutput section, having an output shaft to which rotation of the motorshaft is transmitted via the speed reducer; and a housing, configured toaccommodate the motor unit, the speed reducer, the circuit board and theoutput section. The housing has a motor case that opens at one side inthe axial direction, and a circuit board case attached to one side ofthe motor case in the axial direction to close an opening of the motorcase and configured to accommodate the circuit board. The motor case hasa motor case main body configured to accommodate the motor unit, and aplurality of attaching leg sections protruding from the motor case mainbody and fixed to the vehicle. At least one of the attaching legsections includes an axial projection, protruding from the motor casemain body to another side in the axial direction; and a radialprojection, protruding from a lower end portion of the axial projectiontoward an outer side in the radial direction, and the radial projectionprotrudes outward the circuit board case when seen in the axialdirection. And, the output shaft is connected to a driven shaft from theanother side in the axial direction

According to an aspect of the disclosure, it is possible to provide anelectric actuator having a structure capable of reducing labor forattachment to a vehicle.

The above and other elements, features, steps, characteristics anddetails of the disclosure will become more apparent from the followingdetailed description of the embodiments with reference to the attacheddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example only, withreference to the accompanying drawings which are meant to be exemplary,not limiting, and wherein like elements are numbered alike in severalFigures, in which:

FIG. 1 is a perspective view showing an electric actuator of anembodiment.

FIG. 2 is a view showing the electric actuator of the embodiment asviewed from above.

FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2,showing the electric actuator of the embodiment.

FIG. 4 is a perspective view showing an output section and a speedreducer of the embodiment.

FIG. 5 is a view showing a circuit board case of the embodiment asviewed from below.

FIG. 6 is a perspective view showing a metal member of the embodiment.

FIG. 7 is a perspective view showing a motor case of the embodiment.

DESCRIPTION OF THE EMBODIMENTS

In the drawings, a Z-axis direction is an upward/downward direction inwhich a positive side is directed upward and a negative side is directeddownward. An axial direction of a central axis J1 that is a virtual axisappropriately shown in the drawings is parallel to the Z-axis direction,i.e., the upward/downward direction. An X-axis direction is a directionperpendicular to the Z-axis direction. A Y-axis direction is a directionperpendicular to both of the Z-axis direction and the X-axis direction.In the following description, a direction parallel to the axialdirection of the central axis J1 is simply referred to as “an axialdirection Z,” a direction parallel to the X-axis direction is simplyreferred to as “a first direction X” and a direction parallel to theY-axis direction is simply referred to as “a second direction Y.” Inaddition, a radial direction about the central axis J1 is simplyreferred to as “a radial direction” and a circumferential directionabout the central axis J1 is simply referred to as “a circumferentialdirection” unless the context clearly indicates otherwise. In theembodiment, an upper side corresponds to one side in the axialdirection. Further, upper and lower sides are simply names fordescribing relative positional relations of parts, and an actualdispositional relation or the like may be a dispositional relation orthe like other than the dispositional relations or the like indicated bythese names.

An electric actuator 10 of the embodiment shown in FIG. 1 to FIG. 3 isattached to a vehicle. More specifically, the electric actuator 10 ismounted on an actuator apparatus using a shift-by-wire method driven onthe basis of a shift operation of a driver in the vehicle. As shown inFIG. 3, the electric actuator 10 includes a motor unit 40, a speedreducer 50, an output section 60, a circuit board 70, a motor unitsensor 71, an output section sensor 72, a housing 11, a bus bar holder90, and a bus bar (not shown).

The motor unit 40 has a motor shaft 41, a first bearing 44 a, a secondbearing 44 b, a third bearing 44 c, a fourth bearing 44 d, a rotor mainbody 42, a stator 43, a sensor magnet 45 for a motor unit, and a magnetholder 46. The motor shaft 41 extends in the axial direction Z.

The first bearing 44 a, the second bearing 44 b, the third bearing 44 cand the fourth bearing 44 d support the motor shaft 41 to be rotatablearound the central axis J1. In the embodiment, the first bearing 44 a,the second bearing 44 b, the third bearing 44 c and the fourth bearing44 d are, for example, ball bearings.

An eccentric shaft section 41 a that is a portion of the motor shaft 41supported by the third bearing 44 c has a columnar shape parallel to thecentral axis J1 and extending about an eccentric shaft J2 eccentric withrespect to the central axis J1. A portion of the motor shaft 41 otherthan the eccentric shaft section 41 a has a columnar shape extendingabout the central axis J1.

The rotor main body 42 is fixed to the motor shaft 41. Morespecifically, the rotor main body 42 is fixed to a lower portion of themotor shaft 41. The rotor main body 42 has a rotor core 42 a and a rotormagnet 42 b. The rotor core 42 a is fixed to an outer circumferentialsurface of a portion of the motor shaft 41 below the eccentric shaftsection 41 a. The rotor magnet 42 b is fixed to an outer circumferentialsection of the rotor core 42 a.

The stator 43 is disposed on an outer side of the rotor main body 42 inthe radial direction with a gap. The stator 43 has an annular shape thatsurrounds an outer side of the rotor main body 42 in the radialdirection. The stator 43 has a stator core 43 a, an insulator 43 b and aplurality of coils 43 c. The coils 43 c are mounted on the stator core43 a via the insulator 43 b.

The magnet holder 46 is formed in an annular shape about the centralaxis J1. The magnet holder 46 is fixed to an outer circumferentialsection of an upper end portion of the motor shaft 41. The sensor magnet45 for a motor unit is formed in an annular plate shape about thecentral axis J1. A plate surface of the sensor magnet 45 for a motorunit is perpendicular to the axial direction Z. The sensor magnet 45 fora motor unit is fixed to an outer circumferential edge portion of alower surface of the magnet holder 46 in the radial direction.Accordingly, the sensor magnet 45 for a motor unit is attached to themotor shaft 41 via the magnet holder 46. In the embodiment, the sensormagnet 45 for a motor unit is attached to a portion of the motor shaft41 protruding above the circuit board 70, and faces an upper surface ofthe circuit board 70 via a gap.

The speed reducer 50 is connected to an upper side of the motor shaft41. The speed reducer 50 is disposed over the rotor main body 42 and thestator 43. The speed reducer 50 has an external gear 51, an internalgear 52 and an output gear 53.

As shown in FIG. 3 and FIG. 4, the external gear 51 is formed in anannular plate shape spreading in the radial direction of the eccentricshaft J2 about the eccentric shaft J2 of the eccentric shaft section 41a. A gear section is formed on an outer surface of the external gear 51in the radial direction. The external gear 51 is connected to the motorshaft 41 via the third bearing 44 c. Accordingly, the speed reducer 50is connected to the motor shaft 41. The external gear 51 is fitted ontoan outer wheel of the third bearing 44 c from an outer side in theradial direction. Accordingly, the third bearing 44 c connects the motorshaft 41 and the external gear 51 to be relatively rotatable around theeccentric shaft J2.

The external gear 51 has a plurality of holes 51 a passing through theexternal gear 51 in the axial direction Z. The plurality of holes 51 aare disposed about the eccentric shaft J2 throughout the circumferencein the circumferential direction at equal intervals. As shown in FIG. 4,a shape of the holes 51 a seen in the axial direction Z are circularshapes.

The internal gear 52 is fixed to a circuit board case 20 whilesurrounding an outer side of the external gear 51 in the radialdirection, and meshed with the external gear 51. The internal gear 52 isheld by a metal member 22 (to be described below) of the housing 11. Theinternal gear 52 has an internal gear main body 52 a and a plurality ofprotrusion sections 52 b. The internal gear main body 52 a is formed inan annular shape about the central axis J1. A gear section is formed onan inner circumferential surface of the internal gear main body 52 a.The gear section of the internal gear main body 52 a is meshed with thegear section of the external gear 51. The protrusion sections 52 bprotrude from an outer circumferential section of the internal gear mainbody 52 a toward an outer side in the radial direction. The plurality ofprotrusion sections 52 b are disposed throughout the circumference inthe circumferential direction at equal intervals.

The output gear 53 has an output gear main body 53 a and a plurality ofpins 53 b. The output gear main body 53 a is disposed below the externalgear 51 and the internal gear 52. The output gear main body 53 a has anannular plate shape spreading in the radial direction about the centralaxis J1. A gear section is formed on an outer surface of the output gearmain body 53 a in the radial direction. The gear section of the outputgear main body 53 a protrudes toward an outer side of the internal gearmain body 52 a in the radial direction. As shown in FIG. 3, the outputgear main body 53 a is connected to the motor shaft 41 via the fourthbearing 44 d.

The plurality of pins 53 b have cylindrical shapes protruding upwardfrom an upper surface of the output gear main body 53 a. As shown inFIG. 4, the plurality of pins 53 b are disposed throughout thecircumference in the circumferential direction at equal intervals. Anouter diameter of each of the pins 53 b is smaller than an innerdiameter of each of the holes 51 a. The plurality of pins 53 b passthrough the plurality of holes 51 a from below. An outer circumferentialsection of each of the pins 53 b is inscribed by an innercircumferential surface of one of the holes 51 a. The innercircumferential surfaces of the holes 51 a swingably support theexternal gear 51 around the central axis J1 via the pins 53 b.

The output section 60 is a portion configured to output a driving forceof the electric actuator 10. As shown in FIG. 3, the output section 60is disposed outside the motor unit 40 in the radial direction. Theoutput section 60 has an output shaft 61, a driving gear 62, a sensormagnet 63 for an output section, and a magnet holder 64.

As shown in FIG. 4, the output shaft 61 has a cylindrical shapeextending in the axial direction Z of the motor shaft 41. In this way,since the output shaft 61 extends in the same direction as the motorshaft 41, a structure of the speed reducer 50 configured to transmitrotation of the motor shaft 41 to the output shaft 61 can be simplified.In the embodiment, the output shaft 61 has a cylindrical shape about anoutput central axis J3 that is a virtual axis. The output central axisJ3 is parallel to the central axis J1 and disposed apart from thecentral axis J1 in the radial direction. That is, the motor shaft 41 andthe output shaft 61 are disposed apart in the radial direction of themotor shaft 41.

As shown in FIG. 3, the output shaft 61 has an opening section 61 d thatopens downward. In the embodiment, the output shaft 61 opens at bothsides in the axial direction. The output shaft 61 has a spline grooveformed at a lower section of an inner circumferential surface thereof.The output shaft 61 has an output shaft main body 61 a formed in acylindrical shape, and a flange section 61 b protruding from the outputshaft main body 61 a toward an outer side of the output central axis J3in the radial direction. The output shaft 61 is disposed at a positionoverlapping the rotor main body 42 in the radial direction of the motorshaft 41. A lower end portion of the output shaft 61, i.e., the openingsection 61 d is disposed above a lower end portion of the motor unit 40.In the embodiment, the lower end portion of the motor unit 40 is a lowerend portion of the motor shaft 41.

A driven shaft DS is inserted and connected to the output shaft 61 viathe opening section 61 d from below. More specifically, since a splinesection formed on an outer circumferential section of the driven shaftDS is fitted into a spline groove formed in an inner circumferentialsurface of the output shaft 61, the output shaft 61 and the driven shaftDS are connected to each other. A driving force of the electric actuator10 is transmitted to the driven shaft DS via the output shaft 61.Accordingly, the electric actuator 10 rotates the driven shaft DS aroundthe output central axis J3.

As described above, a side in the axial direction Z in which the openingsection 61 d into which the driven shaft DS is inserted opens is thesame side as that on which the motor unit 40 is disposed with respect tothe speed reducer 50. For this reason, the motor unit 40 can be disposedon a side of an attachment object to which the electric actuator 10 isattached. Accordingly, in the radial direction of the driven shaft DS, aspace outside the driven shaft DS can be used as a space in which themotor unit 40 is disposed. Accordingly, the electric actuator 10 can beattached to the attachment object in a state in which the electricactuator 10 is closer to the attachment object. For this reason,according to the embodiment, it is possible to obtain the electricactuator 10 capable of decreasing an attachment height when attached tothe attachment object. In the embodiment, the attachment object is avehicle.

In addition, according to the embodiment, a direction in which the motorshaft 41 extends from the motor unit 40 toward the speed reducer 50 isan upward direction, which is opposite to a direction in which theopening section 61 d of the output shaft 61 opens. For this reason, adirection in which the output shaft 61 extends from the speed reducer 50may be a direction opposite to a direction in which the motor shaft 41extends from the motor unit 40 toward the speed reducer 50. Accordingly,the motor shaft 41 and the output shaft 61 can be disposed to overlapeach other in the radial direction of the motor shaft 41, and theelectric actuator 10 can be reduced in size in the axial direction Z. Inaddition, since the output shaft 61 overlaps the rotor main body 42 inthe radial direction of the motor shaft 41, the electric actuator 10 canbe further reduced in size in the axial direction Z. Accordingly, anattachment height of the electric actuator 10 is more easily decreasedwhen attached to the attachment object.

In addition, according to the embodiment, a lower end portion of themotor unit 40 is disposed below the opening section 61 d. For thisreason, the motor unit 40 can be disposed closer to the attachmentobject. Accordingly, an attachment height of the electric actuator 10 ismore easily decreased when attached to the attachment object.

The driving gear 62 is fixed to the output shaft 61 and meshed with theoutput gear 53. In the embodiment, the driving gear 62 is fixed to aportion of an outer circumferential section of the output shaft mainbody 61 a above the flange section 61 b. The driving gear 62 comes incontact with an upper surface of the flange section 61 b. As shown inFIG. 4, the driving gear 62 is a fan-shaped gear extending from theoutput shaft 61 toward the output gear 53 and having a width that isincreased toward the output gear 53. A gear section is formed on an endportion of the driving gear 62 on the side of the output gear 53. Thegear section of the driving gear 62 is meshed with the gear section ofthe output gear 53.

As shown in FIG. 3, the magnet holder 64 is a substantially cylindricalmember extending in the axial direction Z about the output central axisJ3. The magnet holder 64 opens at both sides in the axial direction. Themagnet holder 64 is disposed above the output shaft 61 and outside thespeed reducer 50 in the radial direction. The magnet holder 64 passesthrough the circuit board 70 in the axial direction Z. An inner side ofthe magnet holder 64 is connected to an inner side of the output shaft61. An upper end portion of the driven shaft DS inserted into the outputshaft 61 is press-fitted into the magnet holder 64. Accordingly, themagnet holder 64 is fixed to the driven shaft DS.

The sensor magnet 63 for an output section has an annular shape aboutthe output central axis J3. The sensor magnet 63 for an output sectionis fixed to an outer circumferential section in an upper end portion ofthe magnet holder 64. Since the magnet holder 64 is fixed to the drivenshaft DS, the sensor magnet 63 for an output section is fixed to thedriven shaft DS via the magnet holder 64. The sensor magnet 63 for anoutput section faces an upper surface of the circuit board 70 via a gap.

When the motor shaft 41 is rotated around the central axis J1, theeccentric shaft section 41 a revolves about the central axis J1 in thecircumferential direction. Revolution of the eccentric shaft section 41a is transmitted to the external gear 51 via the third bearing 44 c, andthe external gear 51 swings while positions at which the innercircumferential surfaces of the holes 51 a inscribe the outercircumferential sections of the pins 53 b vary. Accordingly, a positionat which the gear section of the external gear 51 is meshed with thegear section of the internal gear 52 varies in the circumferentialdirection. Accordingly, a rotating force of the motor shaft 41 istransmitted to the internal gear 52 via the external gear 51.

Here, in the embodiment, the internal gear 52 is not rotated because theinternal gear 52 is fixed. For this reason, the external gear 51 isrotated around the eccentric shaft J2 by a reaction force of a rotatingforce transmitted to the internal gear 52. Here, a direction in whichthe external gear 51 is rotated is a direction opposite to a directionin which the motor shaft 41 is rotated. Rotation of the external gear 51around the eccentric shaft J2 is transmitted to the output gear 53 viathe holes 51 a and the pins 53 b. Accordingly, the output gear 53 isrotated around the central axis J1. Rotation of the motor shaft 41 isreduced and then transmitted to the output gear 53.

When the output gear 53 is rotated, the driving gear 62 meshed with theoutput gear 53 is rotated around the output central axis J3.Accordingly, the output shaft 61 fixed to the driving gear 62 is rotatedaround the output central axis J3. In this way, rotation of the motorshaft 41 is transmitted to the output shaft 61 via the speed reducer 50.

The circuit board 70 is disposed above the rotor main body 42. Thecircuit board 70 is disposed above the speed reducer 50. The circuitboard 70 has a plate shape with a plate surface perpendicular to theaxial direction Z. While not shown, a shape of the circuit board 70 seenin the axial direction Z is a shape in which one corner portion of aquadrangular shape is chamfered. That is, a shape of the circuit board70 seen in the axial direction Z is a pentagonal shape. The circuitboard 70 has a through-hole 70 a passing through the circuit board 70 inthe axial direction Z. The motor shaft 41 passes through thethrough-hole 70 a. Accordingly, the motor shaft 41 passes through thecircuit board 70 in the axial direction Z. The circuit board 70 iselectrically connected to the stator 43 via the bus bar (not shown).That is, the circuit board 70 is electrically connected to the motorunit 40.

The motor unit sensor 71 is fixed to an upper surface of the circuitboard 70. More specifically, the motor unit sensor 71 is fixed to aportion of an upper surface of the circuit board 70 facing the sensormagnet 45 for a motor unit via a gap in the axial direction Z. The motorunit sensor 71 is a magnetic sensor configured to detect a magneticfield of the sensor magnet 45 for a motor unit. The motor unit sensor 71is, for example, a Hall element. While not shown, for example, threemotor unit sensors 71 are installed in the circumferential direction.The motor unit sensor 71 detects rotational displacement of the sensormagnet 45 for a motor unit and detects rotation of the motor shaft 41 bydetecting a magnetic field of the sensor magnet 45 for a motor unit.

In the embodiment, the speed reducer 50 is connected to an upper side ofthe motor shaft 41, and the circuit board 70 is disposed above the rotormain body 42 and on an upper side of the speed reducer 50. For thisreason, the speed reducer 50 is disposed between the circuit board 70and the rotor main body 42 in the axial direction Z. Accordingly, themotor unit sensor 71 fixed to the circuit board 70 can be disposed apartfrom the rotor main body 42 and the stator 43. Accordingly, the motorunit sensor 71 is less susceptible to the influence of the magneticfield generated from the rotor main body 42 and the stator 43, anddetection accuracy of the motor unit sensor 71 can be improved.

The output section sensor 72 is fixed to an upper surface of the circuitboard 70. More specifically, the output section sensor 72 is fixed to aportion of an upper surface of the circuit board 70 facing the sensormagnet 63 for an output section via a gap in the axial direction Z. Theoutput section sensor 72 is a magnetic sensor configured to detect amagnetic field of the sensor magnet 63 for an output section. The outputsection sensor 72 is, for example, a Hall element. While not shown, forexample, three output section sensors 72 are installed about the outputcentral axis J3 in the circumferential direction. The output sectionsensor 72 detects rotational displacement of the sensor magnet 63 for anoutput section and detects rotation of the driven shaft DS by detectinga magnetic field of the sensor magnet 63 for an output section.

According to the embodiment, the driving gear 62 configured to transmita rotational driving force to the output gear 53 can be disposed toapproach the sensor magnet 63 for an output section by a configurationin which the speed reducer 50 is disposed closer to the circuit board 70than to the motor unit 40. For this reason, a distance in the axialdirection Z from a portion of the output gear 53 to which a rotationaldriving force is transmitted to a portion to which the sensor magnet 63for an output section is fixed can be reduced, and axial deviation ofthe driven shaft DS in a portion to which the sensor magnet 63 for anoutput section is fixed can be minimized. Accordingly, rotationdetection accuracy of the driven shaft DS by the output section sensor72 can be improved.

The housing 11 accommodates the motor unit 40, the speed reducer 50, theoutput section 60, the circuit board 70, the motor unit sensor 71, theoutput section sensor 72, the bus bar holder 90 and the bus bar (notshown). The housing 11 has a motor case 30 and the circuit board case20. The motor case 30 opens upward. As shown in FIG. 1 to FIG. 3, themotor case 30 has a motor case main body 31, a plurality of attachingleg sections 34, 35 and 36, and a stator fixing member 37. That is, thehousing 11 has the motor case main body 31, the plurality of attachingleg sections 34, 35 and 36, and the stator fixing member 37. The circuitboard case 20 has a substantially rectangular parallelepiped box shape.As shown in FIG. 3, the circuit board case 20 closes the opening of themotor case 30 attached to an upper side of the motor case 30. Thecircuit board case 20 accommodates the circuit board 70. The circuitboard case 20 has a circuit board case main body 21, the metal member 22and a circuit board case cover 26. That is, the housing 11 has thecircuit board case main body 21, the metal member 22 and the circuitboard case cover 26.

The circuit board case main body 21 and the motor case main body 31 areformed of a resin. In the embodiment, a housing main body 11 a isconstituted by the circuit board case main body 21 and the motor casemain body 31. That is, the housing 11 has the housing main body 11 aformed of a resin. As shown in FIG. 2, the housing main body 11 a has apolygonal shape when seen in the axial direction Z. More specifically,the housing main body 11 a has a shape in which one corner portion of aquadrangular shape is chamfered when seen in the axial direction Z. Thatis, the housing main body 11 a has a pentagonal shape when seen in theaxial direction Z. The quadrangular shape, one corner portion of whichis chamfered, is a substantially square shape including a pair of sidesextending in the first direction X and a pair of sides extending in thesecond direction Y.

In the embodiment, a shape of the circuit board case main body 21 whenseen in the axial direction Z is equal to a shape of the circuit boardcase 20 when seen in the axial direction Z. The motor case main body 31is disposed inside an external shape of the circuit board case main body21, i.e., inside an external shape of the circuit board case 20, whenseen in the axial direction Z. For this reason, in the embodiment, ashape of the housing main body 11 a when seen in the axial direction Zis equal to a shape of the circuit board case 20 when seen the axialdirection Z. Further, in the specification, a shape of a certain memberwhen seen in the axial direction Z includes a shape of the outermostshape of a certain member when seen in the axial direction Z.

A two-dot chain line appropriately shown in the drawings is a diagonalline D of the housing main body 11 a when seen in the axial direction Z.In addition, the D-axial direction appropriately shown in the drawingsshows a direction parallel to the diagonal line D. As shown in FIG. 5,in the embodiment, the motor shaft 41 and the output shaft 61 aredisposed to be arranged along the diagonal line D of the housing mainbody 11 a when seen in the axial direction Z. The output shaft 61 isdisposed on a corner portion of the housing main body 11 a when seen inthe axial direction Z. In this way, since the motor shaft 41 and theoutput shaft 61 are disposed using the diagonal line D of the housingmain body 11 a having a polygonal shape when seen in the axial directionZ, even when the motor shaft 41 and the output shaft 61 are disposedapart from each other in the radial direction, the entire electricactuator 10 can be easily reduced in size. Accordingly, according to theembodiment, the electric actuator 10 having a structure in which themotor shaft 41 and the output shaft 61 are disposed apart from eachother in the radial direction and a size thereof can be reduced in theradial direction is obtained.

In the specification, “the motor shaft and the output shaft are disposedto be arranged along a diagonal line of the housing main body when seenin the axial direction” means that a direction in which the motor shaftand the output shaft are arranged may be a direction in which a diagonalline extends, or the motor shaft and the output shaft may not overlapthe diagonal line when seen in the axial direction.

In addition, in the specification, “the output shaft is disposed on acorner portion of the housing main body when seen in the axialdirection” includes that, for example, when a perpendicular bisector isdrawn from a center of the housing main body to each side constitutingan outer shape of the housing main body when seen in the axialdirection, the output shaft is disposed in one region separated by theperpendicular bisector, and the output shaft is disposed at a positionclose to an apex of an outer shape of the housing main body with respectto the center of the housing main body.

In addition, according to the embodiment, the driving gear 62 is afan-shaped gear extending from the output shaft 61 toward the outputgear 53 and having a width that is increased toward the output gear 53.For this reason, in comparison with the case in which a circular drivinggear is used, even when the output shaft 61 is disposed on the cornerportion of the housing main body 11 a, the driving gear 62 can bedisposed without increasing the size of the housing 11. Accordingly, theelectric actuator 10 can be further reduced in size.

In the embodiment, the motor shaft 41 is disposed on the central sectionof the housing main body 11 a when seen in the axial direction Z. Forthis reason, a region in which the speed reducer 50 connected to themotor shaft 41 is disposed is easily secured while reducing the size ofthe housing 11.

In the specification, “the motor shaft is disposed on a central sectionof the housing main body when seen in the axial direction” includes, forexample, that the motor shaft is disposed to overlap a region close to acenter of the housing main body in a direction from the center of thehousing main body toward a contour line when seen in the axialdirection.

As shown in FIG. 3, the circuit board case main body 21 has a box shapethat opens upward. As shown in FIG. 2, the circuit board case main body21 has a polygonal shape when seen in the axial direction Z. Morespecifically, the circuit board case main body 21 has a shape in whichone corner portion of a quadrangular shape is chamfered when seen in theaxial direction Z. That is, the circuit board case main body 21 has apentagonal shape when seen in the axial direction Z. A placecorresponding to a portion of the circuit board case main body 21, acorner portion of a quadrangular shape of which is chamfered, isreferred to as a chamfer 21 e. The chamfer 21 e also corresponds to aportion of the housing main body 11 a, a corner portion of thequadrangular shape of which is chamfered. The circuit board case mainbody 21 is larger than the motor case main body 31 and overlaps theentire motor case main body 31 when seen in the axial direction Z.

As shown in FIG. 3, the circuit board case main body 21 has a bottomwall 21 a and a sidewall 21 b. That is, the circuit board case 20 hasthe bottom wall 21 a and the sidewall 21 b. The bottom wall 21 a spreadsalong a plan perpendicular to the axial direction Z. The bottom wall 21a spreads further outward in the radial direction than the motor casemain body 31 when seen in the axial direction Z. The bottom wall 21 acloses an opening on an upper side of the motor case 30. The bottom wall21 a covers an upper side of the stator 43.

The bottom wall 21 a has a concave section 21 c recessed upward from alower surface of the bottom wall 21 a. As shown in FIG. 5, the concavesection 21 c extends along the diagonal line D. As shown in FIG. 3, thebottom wall 21 a has a central through-hole 21 d passing through thebottom wall 21 a in the axial direction Z. The central through-hole 21 dpasses through the bottom wall 21 a from a bottom surface of the concavesection 21 c toward an upper surface of the bottom wall 21 a. Thecentral through-hole 21 d has a circular shape about the central axis J1when seen in the axial direction Z. The motor shaft 41 passes throughthe central through-hole 21 d.

The sidewall 21 b has a rectangular cylindrical shape protruding upwardfrom an outer edge portion of the bottom wall 21 a. The circuit board 70is accommodated inside the sidewall 21 b. That is, the circuit boardcase 20 accommodates the circuit board 70 above the bottom wall 21 a.The sidewall 21 b opens upward. An upper opening of the sidewall 21 b,i.e., an upper opening of the circuit board case 20 is covered by thecircuit board case cover 26. The circuit board case cover 26 is formedof, for example, a metal.

As shown in FIG. 1 and FIG. 2, a first connector section 81 and a secondconnector section 82 are provided on the circuit board case 20. That is,the electric actuator 10 includes the first connector section 81 and thesecond connector section 82. The first connector section 81 and thesecond connector section 82 are portions to which an external apparatusis connected. The external apparatus is, for example, a power supplyapparatus or the like configured to supply power to the motor unit 40.

As shown in FIG. 2, the first connector section 81 and the secondconnector section 82 protrude outward from the housing main body 11 a,i.e., outward from the circuit board case 20 when seen in the axialdirection Z. In the embodiment, the first connector section 81 and thesecond connector section 82 protrude from the circuit board case 20toward one side in the first direction X. The first connector section 81and the second connector section 82 are disposed to be arranged in thesecond direction Y perpendicular to the axial direction Z when seen inthe axial direction Z. The first connector section 81 and the secondconnector section 82 each has a rectangular cylindrical shape that openstoward a side opposite to the circuit board case 20 in the firstdirection X.

The metal member 22 is formed of a metal. As shown in FIG. 3, the metalmember 22 is held by the circuit board case main body 21. That is, themetal member 22 is held by the housing main body 11 a. The metal member22 is accommodated in and held by the concave section 21 c. In theembodiment, a part of the metal member 22 is buried in the housing mainbody 11 a. For this reason, a part or the whole of the housing main body11 a can be fabricated through insert molding in which the metal member22 is inserted into a mold and a resin is poured thereinto. Accordingly,fabrication of the housing 11 is facilitated. In the embodiment, thecircuit board case main body 21 of the housing main body 11 a isfabricated through insert molding in which the metal member 22 isinserted into a mold and a resin is poured thereinto.

As shown in FIG. 6, the metal member 22 has a bearing holding section23, an arm section 25 and an output shaft support section 24. Thebearing holding section 23 has an annular plate section 23 a, an outercylindrical section 23 b, an inner cylindrical section 23 c and a topplate section 23 d. The annular plate section 23 a has an annular plateshape about the central axis J1. A plate surface of the annular platesection 23 a is perpendicular to the axial direction Z.

The outer cylindrical section 23 b has a cylindrical shape protrudingdownward from an outer circumferential edge portion of the annular platesection 23 a. The outer cylindrical section 23 b has a plurality ofslits 23 e passing through a wall section of the outer cylindricalsection 23 b in the radial direction. The plurality of slits 23 e aredisposed throughout the circumference in the circumferential directionat equal intervals. The slits 23 e open downward.

As shown in FIG. 3, the internal gear 52 is held inside the outercylindrical section 23 b in the radial direction. Accordingly, the speedreducer 50 is held by a lower surface of the bottom wall 21 a via themetal member 22. While not shown, the protrusion sections 52 b of theinternal gear 52 are inserted into the slits 23 e, respectively.Accordingly, the protrusion sections 52 b can be suppressed from beingcaught on the inner surfaces of the slits 23 e, or the internal gear 52can be suppressed from moving with respect to the metal member 22 in thecircumferential direction. The outer cylindrical section 23 b is buriedand held inside the central through-hole 21 d in the radial direction.

The inner cylindrical section 23 c has a cylindrical shape protrudingupward from the inner circumferential edge portion of the annular platesection 23 a. The first bearing 44 a is held inside the innercylindrical section 23 c in the radial direction. Accordingly, thebearing holding section 23 holds the first bearing 44 a. The innercylindrical section 23 c protrudes upward from the bottom wall 21 a. Theinner cylindrical section 23 c is disposed inside the sidewall 21 b inthe radial direction. The inner cylindrical section 23 c passes throughthe circuit board 70 in the axial direction Z via the through-hole 70 a,and protrudes upward from the circuit board 70.

Accordingly, at least a part of the first bearing 44 a held by the innercylindrical section 23 c is inserted through the through-hole 70 a. Forthis reason, the motor shaft 41 can be supported by the first bearing 44a at a position close to a portion of the motor shaft 41 to which thesensor magnet 45 for a motor unit is attached. Accordingly, deviation ofan axis of a portion of the motor shaft 41 to which the sensor magnet 45for a motor unit is attached can be minimized, and deviation of aposition of the sensor magnet 45 for a motor unit can be minimized.Accordingly, a decrease in rotation detection accuracy of the motorshaft 41 by the motor unit sensor 71 can be minimized. In addition,since the first bearing 44 a and the circuit board 70 can be disposed tooverlap each other when seen in the radial direction, the electricactuator 10 can be easily reduced in size in the axial direction Z.

In the specification, “the bearing holding section holds the firstbearing” may mean that the bearing holding section may position thefirst bearing in the radial direction, or the first bearing may not befixed to the bearing holding section. In the embodiment, since the firstbearing 44 a is fitted into the inner cylindrical section 23 c, thefirst bearing 44 a is positioned in the radial direction. The firstbearing 44 a is not fixed to the inner cylindrical section 23 c.

The top plate section 23 d protrudes from an upper end portion of theinner cylindrical section 23 c toward an inner side in the radialdirection. The top plate section 23 d has an annular shape about thecentral axis J1, and a plate surface has a plate shape perpendicular tothe axial direction Z. An upper end portion of the motor shaft 41 isinserted through the inside of the top plate section 23 d. An innercircumferential edge portion of the top plate section 23 d is curveddownward. The top plate section 23 d covers an upper side of the firstbearing 44 a.

A pre-load member 47 is disposed between the top plate section 23 d andthe first bearing 44 a in the axial direction Z. That is, the electricactuator 10 includes the pre-load member 47. The pre-load member 47 isan annular waved washer extending in the circumferential direction. Thepre-load member 47 comes in contact with a lower surface of the topplate section 23 d and an upper end portion of an outer wheel of thefirst bearing 44 a. The pre-load member 47 applies a downward pre-loadto the outer wheel of the first bearing 44 a.

The arm section 25 extends from the bearing holding section 23 toward anouter side of the motor shaft 41 in the radial direction. Morespecifically, the arm section 25 extends from a lower end portion of theouter cylindrical section 23 b in the diagonal line D. As shown in FIG.6, the arm section 25 has a plate shape with a plate surface that isperpendicular to the axial direction Z. The arm section 25 has arectangular shape elongated in a direction in which the diagonal line Dextends when seen in the axial direction Z. The arm section 25 connectsthe bearing holding section 23 and the output shaft support section 24.Accordingly, a size of a portion of the metal member 22 other than thebearing holding section 23 and the output shaft support section 24 canbe minimized to a minimum level, and the metal member 22 is easilyreduced in size. Accordingly, manufacturing costs of the housing 11 canbe easily reduced, and the weight of the housing 11 can be easilyreduced.

The output shaft support section 24 is connected to an outer end portionof the arm section 25 in the radial direction. The output shaft supportsection 24 has an annular shape about the output central axis J3, and aplate shape, a plate surface of which is perpendicular to the axialdirection Z. In this way, according to the embodiment, since the outputshaft support section 24 and the arm section 25 have a plate shape, theoutput shaft support section 24 and the arm section 25 can be easilyfabricated through pressing such as punching, folding, or the like, of ametal plate member. In the embodiment, the metal member 22 is a singlemember fabricated through pressing of a metal plate member.

The output shaft support section 24 has a through-hole 24 a passingthrough the output shaft support section 24 in the axial direction Z. Asshown in FIG. 3, a fitting section 61 c that is an upper end portion ofthe output shaft main body 61 a is fitted into the through-hole 24 a.That is, the output shaft 61 has the fitting section 61 c fitted intothe through-hole 24 a. Accordingly, the output shaft support section 24supports the output shaft 61.

In this way, according to the embodiment, the first bearing 44 a can beheld and the output shaft 61 can be supported by the metal member 22formed of a metal. Accordingly, the motor shaft 41 and the output shaft61 supported by the first bearing 44 a can be disposed with goodrelative positional accuracy. In addition, since the housing main body11 a by which the metal member 22 is held is formed of a resin, thehousing 11 can be reduced in weight. Accordingly, according to theembodiment, the electric actuator 10 having a structure in whichreduction in weight can be achieved and a decrease in relativepositional accuracy of the motor shaft 41 and the output shaft 61 can beminimized is obtained. In addition, since the metal member 22 is formedof a metal, strength and a thermal resistance are higher than those ofthe resin. For this reason, even when an external force and heat areadded to the housing 11, deformation/damage to the metal member 22 canbe minimized, and deviation of the motor shaft 41 and the output shaft61 can be minimized.

In addition, according to the embodiment, since the fitting section 61 cis fitted into the through-hole 24 a, the output shaft 61 can be easilysupported with respect to the metal member 22 and positioning can beeasily performed. Accordingly, assembly of the electric actuator 10 canbe facilitated.

As shown in FIG. 7, the motor case main body 31 has a motoraccommodating section 32 and an output section holding section 33. Themotor accommodating section 32 has a cylindrical shape having a bottomsection and opening upward. The motor accommodating section 32 has acylindrical shape about the central axis J1. As shown in FIG. 3, themotor accommodating section 32 accommodates the motor unit 40. That is,the motor case main body 31 accommodates the motor unit 40.

Further, in the specification, “the motor case main body accommodatesthe motor unit” may include that a part of the motor unit may beaccommodated by the motor case main body or another part of the motorunit may protrude to the outside of the motor case main body. In theembodiment, the motor case main body 31, i.e., the motor accommodatingsection 32 accommodates a lower portion of the motor shaft 41, the rotormain body 42, the stator 43, and the second bearing 44 b.

As shown in FIG. 7, the output section holding section 33 protrudes fromthe motor accommodating section 32 toward an outer side in the radialdirection. The output section holding section 33 has a base section 33 aand an output shaft holding section 33 b. The base section 33 aprotrudes from the motor accommodating section 32 toward an outer sidein the radial direction. A width of the base section 33 a is reducedtoward an outer side in the radial direction when seen in the axialdirection Z. The output shaft holding section 33 b protrudes an outerend portion of the base section 33 a in the radial direction toward bothsides in the axial direction. The output shaft holding section 33 b hasa cylindrical shape about the output central axis J3. The output shaftholding section 33 b opens toward both sides in the axial direction. Theinside of the output shaft holding section 33 b passes through the basesection 33 a in the axial direction Z.

As shown in FIG. 3, a cylindrical bush 65 is fitted into the outputshaft holding section 33 b. A flange section protruding outward in theradial direction about the output central axis J3 is formed on an upperend portion of the bush 65. The flange section of the bush 65 issupported by an upper end portion of the output shaft holding section 33b from below. A portion of the output shaft main body 61 a below theflange section 61 b is fitted into the bush 65. The bush 65 rotatablysupports the output shaft 61 around the output central axis J3. Theflange section 61 b is supported by an upper end portion of the outputshaft holding section 33 b from below via the flange section of the bush65. The opening section 61 d below the output shaft 61 is disposed belowthe bush 65.

As shown in FIG. 7, the attaching leg sections 34, 35 and 36 protrudefrom the motor case main body 31. More specifically, the attaching legsections 34, 35 and 36 protrude outward from the motor accommodatingsection 32 in the radial direction. The attaching leg sections 34, 35and 36 are portions fixed to the vehicle. In this way, according to theembodiment, since the motor case 30 has the attaching leg sections 34,35 and 36, there is no need of a bracket configured to attach theelectric actuator 10 to the vehicle. Accordingly, the number of partswhen attached to the electric actuator 10 can be reduced. Accordingly,according to the embodiment, the electric actuator 10 having a structurein which labor for attachment to the vehicle can be reduced is obtained.

In addition, since the attaching leg sections 34, 35 and 36 are providedin the motor case 30 that accommodates the motor unit 40, a distanceuntil vibrations of the motor unit 40 are transmitted to the vehicle canbe reduced. Accordingly, amplification of vibrations of the motor unit40 and transmission to the vehicle can be minimized. In addition, evenwhen a shape of a portion of the vehicle to which the electric actuator10 is attached is varied, it can easily respond by exchanging only themotor case 30.

As shown in FIG. 2, the attaching leg sections 34, 35 and 36 protrudeoutward from the housing main body 11 a, i.e., outward from the circuitboard case 20 when seen in the axial direction Z. For this reason, theelectric actuator 10 is stably easily attached to the vehicle. At leastone of the attaching leg sections 34, 35 and 36 protrudes from a portionbetween the neighboring corner portions of the housing main body 11 a toan outer side of the housing main body 11 a when seen in the axialdirection Z. For this reason, in comparison with the case in which theattaching leg sections 34, 35 and 36 protrude from the corner portionsof the housing main body 11 a when seen in the axial direction Z, theelectric actuator 10 is easily reduced in size. In the embodiment, allof the attaching leg sections 34, 35 and 36 protrude from the portionsbetween the neighboring corner portions of the housing main body 11 a toan outer side of the housing main body 11 a when seen in the axialdirection Z.

Further, in the embodiment, the neighboring corner portions of thehousing main body 11 a correspond to the neighboring corner portions ofthe circuit board case 20, and the attaching leg sections 34, 35 and 36protrude from the portions between the neighboring corner portions ofthe circuit board case 20 to an outer side of the circuit board case 20when seen in the axial direction Z.

As shown FIG. 7, the attaching leg section 34 protrudes from the motoraccommodating section 32 toward an outer side in the radial direction.In the embodiment, the attaching leg section 34 protrudes in the firstdirection X in the radial direction. A width of the attaching legsection 34 is reduced toward an outer side in the radial direction whenseen in the axial direction Z. A through-hole through which a screw isinserted is formed in the attaching leg section 34 to fix the attachingleg section 34 to the vehicle.

The attaching leg section 35 has an axial projection 35 a protrudingdownward from the motor accommodating section 32, and a radialprojection 35 b protruding from a lower end portion of the axialprojection 35 a toward an outer side in the radial direction. In theembodiment, the radial projection 35 b protrudes in the second directionY in the radial direction. A width of the radial projection 35 b isreduced toward an outer side in the radial direction when seen in theaxial direction Z. A through-hole through which a screw is inserted isformed in the radial projection 35 b to fix the radial projection 35 bto the vehicle.

The attaching leg section 36 has an axial projection 36 a protrudingdownward from the motor accommodating section 32, and a radialprojection 36 b protruding from a lower end portion of the axialprojection 36 a to an outer side in the radial direction. The axialprojection 36 a protrudes downward from the axial projection 35 a. Inthe embodiment, the radial projection 36 b protrudes in a directioncrossing both of the first direction X and the second direction Y in theradial direction. A width of the radial projection 36 b is reducedtoward an outer side in the radial direction when seen in the axialdirection Z. A through-hole through which a screw is inserted is formedin the radial projection 36 b to fix the radial projection 36 b to thevehicle.

At least one of the attaching leg sections 34, 35 and 36 is disposedbetween the first connector section 81 and the second connector section82 when seen in the axial direction Z. In the embodiment, the attachingleg section 34 is disposed between the first connector section 81 andthe second connector section 82 when seen in the axial direction Z. Forthis reason, for example, in comparison with the case in which theattaching leg section 34 is disposed at a side opposite to the firstconnector section 81 and the second connector section 82 in the firstdirection X, a dimension of the electric actuator 10 in the firstdirection X is easily reduced. In addition, for example, in comparisonwith the case in which the attaching leg section 34 is disposed at aside opposite to the attaching leg section 35 in the second direction Y,a dimension of the electric actuator 10 in the second direction Y iseasily reduced. In addition, since the attaching leg section 34 isdisposed between the first connector section 81 and the second connectorsection 82, an increase in size of the electric actuator 10 in thesecond direction Y can be minimized.

At least one of the attaching leg sections 34, 35 and 36 protrudes fromthe chamfer 21 e to an outer side of the housing main body 11 a, i.e.,an outer side of the circuit board case 20 when seen in the axialdirection Z. In the embodiment, the attaching leg section 36 protrudesfrom the chamfer 21 e to an outer side of the housing main body 11 a,i.e., an outer side of the circuit board case 20 when seen in the axialdirection Z. For this reason, in comparison with the case in which theattaching leg section 36 is disposed on a corner portion that is notchamfered, the electric actuator 10 is easily reduced in size.

The attaching leg sections 34, 35 and 36 are formed of a resin. In theembodiment, the motor case main body 31 and the attaching leg sections34, 35 and 36 are formed integrally with each other through injectionmolding. That is, the motor case 30 has a resin member having the motorcase main body 31 and the attaching leg sections 34, 35 and 36, and theresin member is a single member. For this reason, the motor case mainbody 31 and the attaching leg sections 34, 35 and 36 can be easilyfabricated through injection molding.

As shown in FIG. 3, the stator fixing member 37 has a cylindrical shapehaving a bottom section and opening upward. The stator fixing member 37has a cylindrical shape about the central axis J1. The stator fixingmember 37 is fitted into the motor accommodating section 32. A pluralityof through-holes disposed in the circumferential direction are formed ina bottom section of the stator fixing member 37. A plurality ofprotrusions formed on the bottom section of the motor accommodatingsection 32 are fitted into the through-holes of the stator fixing member37, respectively.

An upper end portion of the stator fixing member 37 protrudes upwardfrom the motor accommodating section 32. The second bearing 44 b is heldby the bottom section of the stator fixing member 37. An outercircumferential section of the stator 43 is fixed to an innercircumferential surface of the stator fixing member 37. The statorfixing member 37 is formed of a metal. The motor case 30 is fabricatedthrough, for example, insert molding in which a resin is poured into amold in a state in which the stator fixing member 37 is inserted intothe mold.

The bus bar holder 90 is disposed in an upper opening of the statorfixing member 37. The bus bar holder 90 has a plate shape having anannular shape about the central axis J1, and a plate surface isperpendicular to the axial direction Z. The bus bar holder 90 holds abus bar (not shown). The bus bar holder 90 covers an upper side of thestator 43.

The disclosure is not limited to the above-mentioned embodiment andanother configuration can be employed. The metal member may be held bythe housing main body after the housing main body is fabricated. A shapeof the housing main body is not particularly limited. A shape in whichat least one corner portion of a quadrangular shape is chamfered whenseen in the axial direction may be employed as a shape of the housingmain body. That is, a shape of the housing main body may be a shape inwhich two or more corner portions of a quadrangular shape are chamferedwhen seen in the axial direction. The housing main body may have apolygonal shape other than a pentagonal shape, may have a circular shapeor may have an oval shape when seen in the axial direction. The housingmain body may not be formed of a resin, or may be formed of, forexample, a metal.

The attaching leg section is not particularly limited as long as itprotrudes from the motor case main body and protrudes outward from thecircuit board case when seen in the axial direction. The plurality ofattaching leg sections may protrude from the chamfer of the housing mainbody or may protrude from a space between the first connector sectionand the second connector section when seen in the axial direction. Theattaching leg sections may be separate members from the motor case mainbody. The number of attaching leg sections is not particular limited aslong as they are two or more.

The metal member is not particularly limited. The metal member may beconstituted by connecting the plurality of separate members. The metalmember may not be provided. The first bearing, the second bearing, thethird bearing and the fourth bearing may not be ball bearings and may besliding bearings or the like. A configuration of the speed reducer isnot particularly limited. A direction in which the output shaft extendsmay be different from a direction in which the motor shaft extends.

The opening section of the output shaft into which the driven shaft isinserted may open upward. A position at which the output shaft isdisposed is not particularly limited. The motor shaft may be disposed ona corner portion of the housing main body when seen in the axialdirection. The circuit board may be disposed below the motor unit.

A use of the electric actuator of the above-mentioned embodiment is notparticularly limited as long as it is mounted on the vehicle and may bemounted on an apparatus other than a shift-by-wire type actuatorapparatus. In addition, each of the above-mentioned configurations canbe appropriately combined while being not inconsistent with each other.

Features of the above-described embodiments and the modificationsthereof may be combined appropriately as long as no conflict arises.

While the embodiments of the disclosure have been described above, it isto be understood that variations and modifications will be apparent tothose skilled in the art without departing from the scope and spirit ofthe disclosure. The scope of the disclosure, therefore, is to bedetermined solely by the following claims.

What is claimed is:
 1. An electric actuator attached to a vehicle, andthe electric actuator comprising: a motor unit, having a motor shaftextending in an axial direction; a speed reducer, connected to one sideof the motor shaft in the axial direction; a circuit board, disposed atone side of the speed reducer in the axial direction and electricallyconnected to the motor unit; an output section, having an output shaftto which rotation of the motor shaft is transmitted via the speedreducer; and a housing, configured to accommodate the motor unit, thespeed reducer, the circuit board and the output section, wherein thehousing has: a motor case that opens at one side in the axial direction;and a circuit board case, attached to one side of the motor case in theaxial direction to close an opening of the motor case and configured toaccommodate the circuit board, the motor case has: a motor case mainbody, configured to accommodate the motor unit; and a plurality ofattaching leg sections, protruding from the motor case main body andfixed to the vehicle, and wherein at least one of the attaching legsections comprises: an axial projection, protruding from the motor casemain body to another side in the axial direction; and a radialprojection, protruding from a lower end portion of the axial projectiontoward an outer side in the radial direction, wherein the radialprojection protrudes outward the circuit board case when seen in theaxial direction, wherein the output shaft is connected to a driven shaftfrom the another side in the axial direction.
 2. The electric actuatoraccording to claim 1, wherein the circuit board case has a substantiallypolygonal shape when seen in the axial direction, the motor case mainbody is disposed inside an exterior of the circuit board case when seenin the axial direction, and at least one of the attaching leg sectionsprotrudes from a portion between neighboring corner portions of thecircuit board case to an outer side of the circuit board case when seenin the axial direction.
 3. The electric actuator according to claim 2,further comprising: a first connector section and a second connectorsection to which an external equipment is connected, wherein the firstconnector section and the second connector section protrude outward fromthe circuit board case when seen in the axial direction and are disposedto be arranged in a direction perpendicular to the axial direction, andat least one of the attaching leg sections is disposed between the firstconnector section and the second connector section when seen in theaxial direction.
 4. The electric actuator according to claim 2, whereinthe circuit board case has a shape in which at least one corner portionof a quadrangular shape is chamfered when seen in the axial direction,and at least one of the attaching leg sections protrudes from a portionwhich is chamfered to an outer side of the circuit board case when seenin the axial direction.
 5. The electric actuator according to claim 3,wherein the circuit board case has a shape in which at least one cornerportion of a quadrangular shape is chamfered when seen in the axialdirection, and at least one of the attaching leg sections protrudes froma portion which is chamfered to an outer side of the circuit board casewhen seen in the axial direction.
 6. The electric actuator according toclaim 1, wherein the motor case has a resin member formed of a resin andhaving the motor case main body and the attaching leg section, and theresin member is a single member.
 7. The electric actuator according toclaim 2, wherein the motor case has a resin member formed of a resin andhaving the motor case main body and the attaching leg section, and theresin member is a single member.
 8. The electric actuator according toclaim 3, wherein the motor case has a resin member formed of a resin andhaving the motor case main body and the attaching leg section, and theresin member is a single member.
 9. The electric actuator according toclaim 4, wherein the motor case has a resin member formed of a resin andhaving the motor case main body and the attaching leg section, and theresin member is a single member.
 10. The electric actuator according toclaim 5, wherein the motor case has a resin member formed of a resin andhaving the motor case main body and the attaching leg section, and theresin member is a single member.